Overlay.



No. 648,38l. Patented May l, |900.

\ J. W. BLACKFOBD.

0 V E B L AY.

(Application med. Mar. 31, 1889.)

(No Model.)

EDUCAT R PA 'ER PLATE /N VE N TOI-P Jaw/@awww W/TNESSES YBY ATTORNEYS 'UNITED STATES PATENT OFFICE.

JOHN WV. BLAOKFORD, OF OHEBOYGAN, MICHIGAN.

l SPECIFICATION forming part of Letters Patent No. 648,381, dated May 1, 1900.

Application filed March S1, 1899. Serial No. 711,293. (No specimens.)

To all whom it may concern: Y

Be it known that'I, JOHN W. BLACKFORD,re siding at Cheboygan, in the county of Cheboygan and State of Michigan, have invented certain new and useful Improvements in the Art of Making Overlays, of which the following is a specication. a

This invention relates to improvements in the method of making ready,or, as technically known in printing, the overlay.

Since the general adoption of engraved plates produced by dierent mechanical processes it has been found necessary by reason of the shallow depth of the plates, especially those called half-tone, to exercise greatcare and skill in making ready the form, so as to obtain impressions showing up the delicate lights and shadows of the plates to the very best advantage. The process now commonly employed, meaning providing the tympan with the blanket formed of a number of sheets orlayers of paper cut to suit the lights and shades of the engraved plate and varying in thickness accordingly, requires excessive amount of time and a degree of artistic skill not generally found in the ordinary run of printing establishments. Other processes of forming the overlay have been attempted, among which may be named the application of paint to the foundation-sheet in layers api propriate in thickness to the graduation of the impression desired, the forming upon the foundation-sheet a plastic relief film of varying thickness throughout and hardening the same to form a facing vfor the tympan, another being the providing 0f a hard base having one or more coverings of paper to provide for depressions formed therein agreeing in depth and position with the corresponding height and position of the type or lines of the picture produced on the cut from which the impressions are to be taken. So far as I know none of the latter named processes have been put into practical use, their meth od of production requiring, as it were, skill equal or greater than that required for the ordinary make-ready and frequently more time in the completion thereof than is necessary to produce the ordinary overlay.

My invention seeks to provide a makeready or overlay which will equip the tympan with an imprinting-face having a graduated surface calculated to secure a far more accurate impression, particularly as to the blending of the lights and shadows of the cut, than has been heretofore accomplished by'a careful overlay as ordinarily made.

Another and most essential feature of my invention lies in the making of the overlay in such a manner that the same can be produced -by unskilled labor in a few minutesand a more perfect overlay produced than formerly consu med hours, and sometimesl days, to produce by the ordinary method of cutting and pasting backing-strips.

My invention therefore consists in an overlay and the process of making the same, as will be hereinafter first described in detail and then particularly specified in the appended claims.

In the accompanying drawings I have illustrated diagrammatically the overlay and the method of producing the same,

Figure l represents a finished overlay, the thickened or higher portions thereof being indicated by the dierential shading. Fig. 2 represents a longitudinal section of the same on a somewhat-enlarged scale, and Fig. 3 is a diagrammatic sectional view illustrating the overlay as a part of the tympan and showing how the same impacts with the face of the cut during the operation of making an imprint.

The process of making the overlay by my method is best explained as follows: The cut is locked up in the usual way and the rollers well supplied with ink. After the cut has been made properly ready type-high a clean and firm impression is taken directly upon the tympan upon which the job is to be run.

Having made a suitable impression on the tympan and While the said impression is yet wet, a pinch of powder, composed of a base part having no absorbing qualities (such as emery-flour) and a suitable quantity of soluble blue or any other material that will not form a pasty matter to createv bunches on the tympan, soluble blue being usedas it adheres to the emery Without forming in any injurious quantity, it being the medium of absorption between the ink and emery, is spread over every part of the impression that requires an overlay. In doing this, however, it

is not necessary to exercise great care to keep the powder from touching those parts of the IOO lover the impression at the points required all ordinary effort.

of the powder that can be is blown off by an? This .removes all excessivepowder and leaves only the thickly-inked portions equipped with the powder, the degreeH of absorption of powder being of course governed by the differences between the heavier and lighter inked surfaces. ""While I have specified soluble blue as the ingredient to Vbe used ,with the eme'ry-flour to produce the absorption between the emery and vthe ink, I do not limit myself to 4such particular ingredients, as any other ingredients having like qualities maybe used-as, for example, dragons-blood, (Stragi/.fis dracones). After the foundation impression has been thus treated a thin sheet of paper, which forms the facing, is drawn firmly over the impression. This completesthe overlay,'and the printing may be thenproceeded with.

It should be stated that by providing a pow- 'der composed of a-base having noabsorbent quality and mixing with it sufficient quantity ofan ingredient which will produce the absorption between the emery and the ink a firm relief will be produced upon the tympan opposing the relief face, varying'proportionately to the dierent degrees of the thick or blacksurface of the cut.

In the practical application of my invention I proportion the ingredients by mixing in bulk ninety-five parts of em ery-flour with five parts of soluble blue, it being, however, obvious that these proportions' need not` be strictly adhered to. The'action of the two ingredients is such that the soluble blue. adheres to the emery only lightly and not, in a harmful quantity, its sole office being to aid the ink in retaining the emery. f This method of producing the overlay avoids the necessity of hardening or baking the overlay, as has been attempted heretofore. Furthermore, as the impression is made directly -on the tympan the same need not be removed therefrom, and as the surplus powder Vis blown off from the impression itwill not be necessary to exercise any skill in placing the powder upon the thickened part of the impression. It thereby does not require an expert to make the overlay, as it does by v the old method. Again, the smaller parts of the overlay,very often left out in the old. method, are effectively brought out, which avoids any slighting of the work when one is in a hurry and at the same time producing yen t, is-

that` gradual blending ofthe. high with the dark lightsnecessary toeect a perfcctprinting of the cut. Again, the ingredients specified are in no way injurious to the most delicate cut, and as the vcompound from which y my overlay Ais formed hardens 'the same will not wear out, as do those made in the oldway.

I am aware .that an overlay having a raised portionvformed of a viscid compound impregnated with apasty substance has heretofore been provided. My invention differentiates from-such form of overlay in that a surface formed of a yiscid com pound must be removed from the Jtympan and subjected to a baking process before it will have a sufficient tenacity or be hardened so it will stand'as an overlay, While by my'process the overlay is formed on the tympan andy need not be removed therefrom for any special treatment, the rbody or vcompound being initially of a harder lmaterial requires no baking'or hardening process to put it in condition for use.

Having thus described my invention, what 1 claim,.and desire to secure by Letters Pat- 1. The method of forming an overlay, consisting in constructing the raised portion thereof on thetympanfrom a-compoundhav ing as its base an extremely-hard granular material impregnated with an ink-absorbin g ingredient, substantiallyl as set forth.

2., The method of forming an overlay, con sisting in making an impression onthe tympan 5 adding a powdered Compound tothe surface of the impression at such portion where the overlay is to be had, said compound having as its base an extremely-hard granular substance impregnatedwith an ink-absorbing ingredient, substantially as set forth.

3. The process of forming an overlay con'- sisting in making animpression on thefoundation-sheet; spraying a `pulverulent compound composed of ahard granular substance impregnated with an absorbent materialover those portions of the impression to be overlaid, then blowing olf` the non-absorbed compound, for'th'epurposes specified.`

4. The process of forming an overlay, consisting in making an impression on the foundation or tympan sheet; spraying the said-impression at the points to be overlaid with a compound having as its base emery-flour and an absorbent material such as soluble blue impregnated therewith, then blowing off the unabsorbed powder and then drawing a thin sheet over the same, substantially as set forth.

lJOHN w. BLAGKFORD.

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